Automatic venturi draft control



A ril 28, 1953 c. M. BICKHAM AUTOMATIC VENTURI DRAFT CONTROL Filed Aug; 14, 1950 l3 INVENTOR CL/FFO/ZD M BIC/{HAM Patented Apr. 28, 1953 UNITED srAr OFFICE stalled, carbureter Venturi attachment which functions as an automatic damper responsive to air flow in the Venturi tube.

Other and incidental objects will be apparent from the following description in conjunction with the accompanying drawings, in which:

Figure 1 is an axial sectional view through the Venturi assembly of a carbureter with my novel draft control attachment applied thereto;

Figure 2 is a sectional View at a right angle to the plane of Figure 1, illustrating a mounting detail;

Figure 3 is a perspective view of the damper attaching means employed;

Figure 4 is a perspective view of the damper support separated from the attaching means.

As shown in Figure 1, the control is mounted in a known type of down-draft carbureter 5 having the usual high speed fuel jet nozzle t discharging at an upward incline into the inner main Venturi tube 1 at its upper end. In this known type of carbureter the inner tube '1 is surrounded by a cylindrical outer secondary Venturi tube 8 of larger diameter concentric thereto.

My novel attachment consists of a spider which comprises a base ring 9 of channel cross section and of the same diameter as the tube 8, which is applied upwardly over the lower end of the tube with the tube end engaged in the channel of the ring. The ring is provided at diametrically opposed points with a pair of axially directed parallel spring arms it of the same or slightly greater length than the axial extent of the tube 8, and which have hook terminals ll that are adapted to snap inwardly over the upper end of the tube to anchor the base ring in service position on the tube, as shown in Figure 1.

The base ring is also provided with a damper support l2, here shown as a flat bar extending diametrically across the ring at right angles to the diametric plane of the arms it. The ends of the bar are rigidly connected to the base ring by any suitable means. In the present embodiment of the invention the connection comprises end portions l3 bent over the ring and crimped inwardly over the outer wall of the ring channel.

A fine Wire expansion spring helix M of frustoconical form is seated at its base on the bar l2 and the edge of the inner wall of the base ring channel. The apex portion of the spring mounts a flat annular cap it of imperforate material which normally seats lightly against and closes the lower end of the main Venturi tube 1 by the expansion bias of the spring when no air is being drawn through the Venturi.

When the engine with which the carburettor is associated is running, the draft through the Venturi exerts a pressure on the cap It: so that it is moved downwardly away from the end of the tube a. As the engine speed increases the draft through the Venturi is correspondingly increased and the cap is further depressed. Downward movement of the cap correspondingly collapses the spring i l so that its convolutions are nested, thereby lessening the free cross sectional area of the air passage through the tube 8 and correspondingly decreasing the suction draft on the fuel jet nozzle 6. An excess discharge of gasoline from the high speed nozzle is thus prevented and waste of gasoline, so common in conventional carbureters, is eliminated. In addition, the cap and the fine wire coils of the spring aid in atomizing the charge.

Although the invention is herein shown and described as applied to a particular carbureter of known construction, it is to be understood that it is equally applicable to any type of Venturi carbureter; for example, to those which employ a single large Venturi tube. The essential factor is the disposition within a Venturi tube of an imperforate member carried by a conical spring hellX and responsive to air flow through the tube to contract the coils of the spring against its bias into nesting relation across the line of air now to restrict air now throu h the tube. rurtherinore, it is within the purview DI the invention that any desired changes and variations in structural details may be made, provided they are Within the scope of the invention as claimed.

I claim:

In combination, a Venturi tube, a spider attached at one end thereof, a irusto-conical expansion spring helix seated at its base on the spider with its apex portion extending axially into the tube, and an lmperforate air flow responsive member on said apex portion, said memher being movable axially L]. the "tube to bring the spring coils into nesting relation across the line 01 air flow.

CLIFFORD M. BICKI-IAM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,079,985 Kaminsky Dec. 2, 1913 2,451,387 Harvout Oct. 12, 1948 

